Exchange 2007 introduces a new concept to Exchange organizations, the concept of server roles. Similar to how a Windows server can host one or more roles, this type of configuration has been implemented in Exchange Server 2007.
Server roles allow an administrator to split the functions of an Exchange server and place each role, or a combination of roles, on different servers in the organization. This can be done for performance reasons, management reasons, or any other reason deemed necessary by the organization's policies.
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